Colored printing ink for contact lenses

ABSTRACT

The present invention provides novels inks and methods for making a colored polymeric substrates, preferably a contact lens. In the inventive method at least a portion of a surface of a lens is coated with a color coat comprising at least one colorant, and a binder polymer obtained by copolymerizing a first monomer being ethylenically unsaturated and having a latent crosslinkable pendent group; and a second monomer having an ethylenically unsaturated double bond copolymerizable with the first monomer. The lens is then subjected to conditions that cause the color coat to adhere to the lens.

STATEMENT OF RELATED APPLICATIONS

This patent application is a division of U.S. patent application Ser.No. 10/098,870 filed Mar. 15, 2002, now U.S. Pat. No. 6,955,832 whichclaims priority on provisional application Ser. No. 60/342,199 filedDec. 19, 2001 and 60/276,772 filed Mar. 16, 2001, the entirety of whichare hereby incorporated by reference.

COLORED PRINTING INK FOR CONTACT LENSES

The present invention relates to a method for making a colored printingink that can be applied to contact lenses or to the molds that will beused to make contact lenses. In the latter case, the ink printed on themold surface would be incorporated into the contact lens as contact lensconstituent monomers are then added to the mold and polymerized. Ineither case, the resultant product will be a contact lens to whichcolored ink has been applied.

BACKGROUND OF THE INVENTION

Methods have been disclosed to make printing inks suitable for printingeither contact lenses or the molds that are then used to make contactlenses. For example, U.S. Pat. No. 4,668,240 to Loshaek disclosescolored contact lenses produced by providing a contact lens constructedof polymer and coating at least a portion of the lens with coloringsubstance, a binding polymer having functional groups, and an additionalcompound having at least one of —NCO or epoxy. The lens and bindingpolymers are bonded to each other by the reaction of functional groups.

U.S. Pat. No. 4,857,072 to Narducy, et al. discloses a method for makingcolored hydrophilic contact lenses. At least a portion of the surface ofthe lens is coated with a color coat comprising at least one pigment,binding polymer having functional groups, and an additional compoundhaving at least two groups per molecule of —NCO. The coated lens is thensubjected to conditions that cause the color coat to adhere to the lens.

U.S. Pat. No. 5,272,010 to Quinn discloses a method for preparation ofcolored contact lenses similar to that of U.S. Pat. Nos. 4,668,240 and4,857,072 except that an isocyanate compound is not required. Instead,adhesion promoters such as hexamethoxymethylmelamine are used.

The above-referenced patents (all of which are incorporated herein byreference) are substantially similar in that they all require (a) one ormore pigments to add colorant to the contact lens; (b) one or moremonomers to help the printing ink bind to the contact lens; (c) aninitiator to polymerize the monomers in the printing ink; (d) a binderpolymer with appropriate functional groups; and (e) an adhesion promoterto form crosslinks with the functional groups of the binder polymer. Theadhesion promoter can also chemically bond the binder polymer to thelens polymer.

However, the methods known in the art have several disadvantages. Thefirst disadvantage concerns the potential use of a diluent in themonomer mixture that is polymerized to make contact lenses. A diluent inthe monomer mixture is a well recognized technique for casting contactlenses (U.S. Pat. No. 5,039,459 Larsen-Kindt, et al.). However, adiluent in the monomer mixture and subsequently in the contact lens mayinterfere with the required crosslinking of the binder polymer. This maybe an effect of diluting the concentration of reagents and/or thediluent may react with adhesion promoter to the detriment of the bondingneeded to provide adequate adhesion of the colorant to the contact lens.In any case, the capability of the adhesion promoter to provide adequateadhesion of the colorant to the contact lens is diminished.

The second disadvantage of the current processes is related to therequirement that a separate adhesion promoter in the form of a reagentor a specialty, reactive coating be added to the colored lens printingink. This has all the disadvantages associated with adding an additionalingredient to a manufacturing process.

The third disadvantage is observed in the need for a separate step toreact the adhesion promoter to functional groups of the binder polymer.The most commonly described separate step is a thermal cure and thisnecessitates adding costly equipment to the lens manufacturing process.

The fourth disadvantage is that the printing inks currently used containa polymerization initiator and monomers that must be polymerized in apost-printing operation.

SUMMARY OF THE INVENTION

The present invention comprises a method for making a colored polymersubstrate, preferably a medical device, most preferably a hydrophiliccontact lens, comprising the steps of:

-   -   (a) providing a contact lens constructed of a polymer    -   (b) coating at least a portion of a surface of the lens with a        color coat comprising at least one colorant, and a binder        polymer obtained by copolymerizing polymerizable components        comprising        -   a. an ethylenically unsaturated monomer having a latent            crosslinkable pendent group (hereinafter referred to as a            compound (A)); and        -   b. a monomer (B) which has ethylenically unsaturated double            bond copolymerizable with the compound (A) (hereinafter            referred to as a monomer (B); and    -   (c) subjecting the coated lens to conditions which cause the        color coat to adhere to the lens;    -   wherein monomer (B) is substantially non-reactive with the        latent crosslinkable group of monomer (A).

A second aspect of the invention comprises a method for making a coloredpolymer substrate, preferably a medical device, most preferably ahydrophilic contact lens, comprising the steps of:

-   -   (a) coating at least a portion of at least one lens-forming        surface of a lens mold with a color coat comprising at least one        colorant, and a binder polymer obtained by copolymerizing        polymerizable components comprising        -   a. a monomer (A) as disclosed above; and        -   b. a monomer (B) as disclosed above;    -   (b) adding a lens forming composition to the lens mold while        maintaining the color coat in position;    -   (c) curing the lens-forming composition to form a coated lens;        and    -   (d) subjecting the coated lens to conditions which cause the        color coat to adhere to the lens.    -   wherein monomer (B) is substantially non-reactive with the        latent crosslinkable group of monomer (A).

A third aspect of the invention comprises a printing ink as disclosedabove and a method for use thereof that is substantially free of aseparate adhesion promoter species such as hexamethoxymethylmelamine orhexamethlene diisocyanate. Known adhesion promoter species in printingcontact lenses are described in U.S. Pat. Nos. 4,668,240; 4,857,072; and5,272,010, incorporated herein by reference. Specifically, the inks ofthe present invention are preferably free of isocyanate compounds.

A fourth aspect of the invention comprises a method of forming a contactlens containing an image thereon comprising the step of inkjet printinga moisture curable ink composition of the invention onto a hydrogelcontact lens.

A fifth aspect of the invention comprises polymeric substrates,preferably hydrophilic colored contact lenses, made by the inventivemethods.

DETAILED DESCRIPTION OF THE INVENTION Definitions

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs. Generally, the nomenclatureused herein and the laboratory procedures well known and commonlyemployed in the art. Conventional methods are used for these procedures,such as those provided in the art and various general references. Wherea term is provided in the singular, the inventors also contemplate theplural of that term. The nomenclature used herein and the laboratoryprocedures described below are those well known and commonly employed inthe art. As employed throughout the disclosure, the following terms,unless otherwise indicated, shall be understood to have the followingmeanings:

“Moisture” includes both water and water vapor including atmosphericwater vapor.

“Colorant” includes both dyes and opaque coloring agents, either aloneor in combination.

“Dye” means a substance that is soluble in a solvent and is used toimpart color. Dyes are typically translucent and absorb, but do notscatter light. Dyes can cover both optical (covering the pupil) andnon-optical regions (not covering the pupil) of contact lens. Nearly anydye can be used in the present invention, as long as it is compatiblewith the processes described herein, including fluorescent dyes,phosphorescent dyes, pearlescent dyes, and conventional dyes.

“Fluorescent dyes” include dyes that produce immediate luminescence whenexposed to visible or ultraviolet radiation. Typically, the luminescenceis at a wavelength longer than the wavelength causing the fluorescenceand ceases immediately when the incident light or ultraviolet radiationis stopped.

“Phosphorescent dyes” include dies that produce delayed luminescencewhen exposed to visible or ultraviolet radiation. Typically, theluminescence is at a wavelength different than the wavelength causingthe phosphorescence and continues for a prolonged time after theincident light or ultraviolet radiation is stopped.

“Opaque coloring agent” includes both pigments and particles.

“Pigment” in the context of opaque coloring agents refers to a varietyof organic or inorganic insoluble pigments known in the art, such astitanium dioxide, red iron oxide, yellow iron oxide, Pigment Blue 15(phthalocyanine blue (CI 74160)), Pigment Green 7 (phthalocyanine green(CI 74260)), Pigment Blue 36 (cobalt blue (CI 77343)), or chromiumsesquioxide. Some pigments may exhibit fluorescence or phosphorescence.While specific examples are given throughout this specification, theskilled artisan will recognize that any of a variety of pigments may beused.

“Particle” in the context of opaque coloring agents refers to a varietyof colored particles, as they are known in the art, such as India ink.This term also includes structures that while not colored, give theappearance of color by, for example, diffraction or scattering (forexample) of light by the particle. Some particles may exhibitfluorescence or phosphorescence.

“Ethylenically unsaturated” is employed herein in a broad sense and isintended to encompass, for example, vinyl compounds, acrylic compounds,and methacrylic compounds. The basic criteria with respect to theethylenically unsaturated monomers are that they contain at leastone >C═C< group, that is copolymerizable without gelation with theopposite monomer and does not otherwise preclude the utilization of thefinished pigment binder.

“Lens” as used herein refers to a composition of matter that cantransmit light. A lens preferably can act as an optical lens, such as acontact lens. In certain aspects of the present invention, a lens neednot act as an optical lens, such as a contact lens that is used forvanity purposes as opposed to purposes relating to the correction,improvement, or alteration of a user's eyesight.

“Contact Lens” refers to a structure that can be placed on or within awearer's eye. A contact lens can correct, improve, or alter a user'seyesight, but that need not be the case. A contact lens can be of anyappropriate material known in the art or later developed, and can be asoft lens, a hard lens, or a hybrid lens. A contact lens can be in a drystate or a wet state.

“Dry State” refers to a soft lens in a state prior to hydration or thestate of a hard lens under storage or use conditions.

“Wet State” refers to a soft lens in a hydrated state.

“Hydrogel” refers to a polymer that swells in an aqueous solution due tothe absorbance of water. A hydrogel includes water or an aqueoussolution as part of its structure.

“Polymer” refers to a linkage of monomers. Preferably, a polymer is apolymer appropriate for use in lenses, such as contact lenses. A polymercan be, for example, a homopolymer, a heteropolymer, a copolymer, ahydrophobic polymer, a hydrophilic polymer, or any combination thereof.

“Ophthalmically compatible,” as used herein, refers to a material orsurface of a material which may be in intimate contact with the ocularenvironment for an extended period of time without significantlydamaging the ocular environment and without significant user discomfort.Thus, an ophthalmically compatible contact lens will not producesignificant corneal swelling, will adequately move on the eye withblinking to promote adequate tear exchange, will not have substantialamounts of lipid adsorption, and will not cause substantial wearerdiscomfort during the prescribed period of wear. The lenses of thepresent invention are preferably ophthalmically compatible.

“Ocular environment,” as used herein, refers to ocular fluids (e. g.,tear fluid) and ocular tissue (e.g., the cornea) which may come intointimate contact with a contact lens used for vision correction, drugdelivery, wound healing, eye color modification, or other ophthalmicapplications.

“Hydrophilic,” as used herein, describes a material or portion thereofthat will more readily associate with water than with lipids.

The “front surface” of a lens, as used herein, refers to the surface ofthe lens that faces away from the eye during wear. The front surface,which is typically substantially convex, may also be referred to as thefront curve of the lens.

The “rear surface” of a lens, as used herein, refers to the surface ofthe lens that faces towards the eye during wear. The rear surface, whichis typically substantially concave, may also be referred to as the basecurve of the lens.

“Thickener” refers to compounds that is used to increase the viscosityof a liquid or partially liquid mixture or solution such as that term isknown in the art, An example of a thickener is a polyvinyl alcohol.

“Printing” refers to the application of at least one color coat to asurface or structure to form an image. Printing can use any appropriatedevice or method known in the art of later developed for a particularpurpose.

“Pattern” refers to a predetermined image to be printed onto the contactlenses. The pattern may either be fanciful or realistic in appearance.The pattern is preferably designed in accordance with U.S. Pat. Nos.5,160,463 to Evans et al. and 5,414,477 to Jahnke).

“Nucleophilic” is used in accordance with its well-known meaning andrefers to a compound, composition, or reagent that forms a bond to itsreaction partner by donating both bonding electrons to that reactionpartner.

The present invention provides methods for making a colored hydrophiliccontact lens. In a first embodiment of the invention the methodcomprising the steps of coating at least a portion of a surface of alens with a color coat comprising at least one colorant, preferably apigment, and a binder polymer. The binder polymer is obtained bycopolymerizing polymerizable components comprising an ethylenicallyunsaturated monomer having a latent crosslinkable pendent group; and amonomer (B) which has ethylenically unsaturated double bondcopolymerizable with the compound (A). The lens is then subjected toconditions that cause the color coat to adhere to the lens.Specifically, the binder polymer cross-links, thus entrapping thecolorant and adhering to the lens.

Alternatively, in a preferred embodiment, the color coat can be appliedto a lens-forming surface of a mold for making contact lenses. Apolymerizable or cross-linkable composition is then added to the moldand cured to form a color contact lens onto which the color coat istransferred from the mold to become an integral part of the contactlens. In this method, the colored contact lens has a smooth surface thatmay provide more comfort to the wearer. Suitable methods for printingupon a lens mold are disclosed in U.S. Pat. No. 5,034,166 to Rawlings,et al., incorporated herein by reference.

The color coat that is applied to the lens comprises at least onecolorant, preferably a pigment, and a binder polymer. The binder polymeris obtained by copolymerizing polymerizable components comprising (A) anethylenically unsaturated monomer having a latent crosslinkable pendentgroup (hereinafter referred to as a compound (A)) and a monomer (B)which has ethylenically unsaturated double bond copolymerizable with thecompound (A) (hereinafter referred to as a monomer (B).

The latent crosslinkable pendent group comprises a labile functionalgroup capable of reacting after (A) and (B) are copolymerized tocrosslink the resulting polymer. Possible functional groups includeepoxy, hydroxy, alkenyl, isocyanate, peroxy, perester, anhydride,silane, and combinations thereof.

The latent crosslinking reaction may be activated by moisture,nucleophilic catalysis, heat, or combinations thereof. To allow formoisture-activated crosslinking, incorporating one or more of thefollowing into the compound (A) is desirable: alkoxysilane, silanol,acetoxysilane, silanes, or halosilane groups. Alkoxysilane,acetoxysilane, silanes, or halosilane form silanols upon exposure tomoisture. The silanols react with each other to form siloxane bonds.Therefore, polymer chains containing pendant silanol groups (orprecursors) can combine to form crosslinks through the formation ofsiloxane linkages. Being moisture activated, the crosslinks would formduring hydration of the polymer. The preferred latent crosslinkablependant groups are halosilane and alkoxysilane, with alkoxysilane beingthe most preferred.

Crosslinking reactions involving organosilicon functional groups couldalso occur by non-hydrolytic processes. Halosilanes can form siloxanebonds by being exposed to alkoxy silane, metal oxides (e.g., calciumoxide, magnesium oxide, zinc oxide, copper oxide, etc.) andalcohol+carboxylic acid.

Alkoxysilanes can combine with each other to form siloxane bonds.Crosslinking and curing of silicones is well known (see W. Noll,Chemistry and Technology of Silicones, Academic Press, Inc., London).

In addition, alkoxysilanes also form siloxane bonds when exposed tosilanols, acetoxysilanes, carboxylic acids, and acids such as HCl.Hydrolytic and non-hydrolytic reactions in which siloxane bonds areformed could be used to introduce crosslinks into the color coating onceit is applied to the lens. When water is applied to the lens during thehydration step, crosslinking reactions are initiated, thereby causingthe color coat to adhere to the lens.

The preferred compound (A) is a polymerizable halosilane or alkoxysilanecompound of the formula (I):

wherein X is a polymerizable group containing an unsaturated doublebond; n is an integer from 0 to 12; Z is either a halide or —OR₂; eachR₁ is, independently of any other, a halide, or a substituted orunsubstituted C₁₋₆ alkyl group; R₂ is, independently of any other, asubstituted or unsubstituted C₁₋₆ alkyl group and q is an integer from 1to 3.

In the above formula, X is preferably a (meth)acryloxy group, vinylgroup, an allyl group, or a group of the formula

More preferably, X is a (meth)acryloxy group or a vinyl group; and mostpreferably a methacryloxy group.

The integer n is preferably from 1 to 12; more preferably from 1 to 6;and more preferably from 2 to 4. The most preferred value for n is 2 or3, especially when X is a methacryloxy group. One of ordinary skill inthe art will recognize appropriate n can be determined, through theteachings of this description, by routine experimentation.

Typical examples of the polymerizable alkoxysilane compound (Z is —OR₂in the above formula) include, but are not limited to:methacryloxyethyltrimethoxysilane,methacryloxyethylmethyldimethoxysilane,methacryloxyethyldimethylmethoxysilane,methacryloxyethyltriethoxysilane, methacryloxyethylmethyldiethoxysilane,methacryloxyethyldimethylethoxysilane,methacryloxy-propyltrimethoxysilane,methacryloxypropylmethyldimethoxysilane,methacryloxypropyldimethylmethoxysilane,methacryloxypropyltriethoxysilane,methacryloxypropylmethyldiethoxysilane,methacryloxy-propyldimethylethoxysilane, styrylethyltrimethoxysilane,and 3-(N-styrlmethyl-2-aminoethylamino) propyltrimethoxysilanehydrochloride. These compounds may be used alone or in combination as amixture of two or more of them.

R₂ is preferably an unsubstituted C₁₋₆ alkyl; more preferably anunsubstituted C₁₋₄ alkyl; more preferably an unsubstituted C₁₋₂ alkyl;and most preferably a methyl group. While it is presently preferred thatthe above-mentioned R₂ be unsubstituted alkyl, it should be apparent toone of ordinary skill in the art that any of the above-mentionedpreferable R₂ group could also be substituted as long as suchsubstitution did not interfere with the invention as described herein.Furthermore, it is preferable that each R₂ be the same as other R₂ (ifany) present.

The preferred alkoxysilane compounds are methoxysilanes (Z is —OR₂ andR₂ is methyl). The preferred methoxysilanes includemethacryloxyethyltrimethoxysilane,methacryloxyethylmethyldimethoxysilane, andmethacryloxyethyldimethylethoxysilane.

If Z is a halide, the preferred halide is chloride. Likewise, it ispreferable that each Z be the same as other Z (if any) present.Preferred examples of the polymerizable halosilane compound of the aboveformula (I) include, but are not limited to:methacryloxypropylmethyldichlorosilane,methacryloxypropyltrichlorosilane,3-methacryloxypropyldimethylchlorosilane, andmethacryloxyethyltrichlorosilane.

In the above formula, q can be suitably determined taking the reactivityfor the condensation reaction into consideration.

The amount of the compound (A) in the polymerizable components, ispreferably adjusted to be between 5% and 25%, by weight, of the binder(A+B) in order to sufficiently obtain crosslinking effects.

The monomer (B) that can be used in the present invention, is a monomerwhich has an unsaturated double bond copolymerizable with the compound(A) and which is substantially non-reactive with the latentcrosslinkable group of monomer (A). Specifically, during thepolymerization process, monomer (B) undergoes no crosslinking reactionwith compound (A). Such a monomer (B) may, for example, be one havingone copolymerizable unsaturated double bond, i.e. a monomer other than acrosslinkable monomer or a crosslinkable macromonomer having at leasttwo polymerizable groups. The compound (B) is preferably silicon-free.

However, it should be noted that compound (A) or the combined binderpolymer (A+B) might cross-link in the presence of nucleophilic reagents.Monomers that contain groups having active hydrogen atoms, for example,hydroxy functional groups (e.g. ROH), primary and secondary aminefunctional groups (e.g., RNH₂ or R₂NH), or acid functional groups (e.g.,RCOOH) are likely to cause gelation/crosslinking during copolymerizationwith e.g., alkoxysilanes. As a result, the number of suitable monomers(B) for copolymerization with compound (A) is limited to those that willnot readily undergo a crosslinking reaction with the compound (A).

However, amounts of monomer (B) containing a number of active hydrogensinsufficient to cause premature gelation may be utilized in preparationof the pigment binder. Moreover, if multiple monomers (B) are utilizedin the preparation of the pigment binder, at least one of such monomersshould be substantially free of active hydrogen atoms and the totalweight of those monomers having active hydrogen atoms is less than 10%by weight of the total amount of monomer (B). Preferably, those monomershaving active hydrogen atoms are less than 0.5% by weight of the totalamount of monomer (B).

Typical examples of the monomer (B) lacking active hydrogen atomsinclude a N-vinyl heterocyclic monomers, such as N-vinyl-2-pyrrolidone(NVP); C₁ to C₆ alkyl vinyl ethers, such as vinyl ethyl ether; C₁ to C₆alkyl ester of acrylic or methacrylic acid, such as methyl methacrylateand propyl acrylate; C₁ to C₆ alkyl styrene, such as t-butyl styrene;vinyl monomers, such as vinyl chloride and vinyl acetate; dienemonomers, such as isoprene; and C₁ to C₆ alkoxy C₁ to C₆ alkyl esters ofacrylic or methacrylic acid, such as ethoxyethyl methacrylate (EOEMA) ormethoxypropyl acrylate. These monomers may be used alone or incombination as a mixture of two or more of them.

Alternatively, active hydroxyl groups of monomer (B) can be “masked” orprotected by a solvolyzable group to prevent reaction with the latentcrosslinkable group of monomer (A). By “solvolyzable” it is generallymeant an ester linking group capable of cleaving into acarboxyl-containing compound (e.g., amide, ester, or acid) and analcohol in the presence of a nucleophile such as water or a weak basesuch as ammonia or an organic amine (at room temperature) or in thepresence of a lower (C₁ to C₄) alkanol (at temperatures up to 60° C.).For instance the active hydrogens of glycerol methacrylate can be maskedwith a group such as trichloroacetyl or perfluoracyl. The solvolyzablewould later hydrolyze in the presence of a nucleophile. Such groups aredisclosed in U.S. Pat. No. 4,638,040 to Hammar, incorporated herein byreference.

Preferred monomers (B) include N-vinyl heterocyclic monomers and alkyl(meth)acrylamides. Most preferred are N,N-dimethyl acrylamide (DMA) andN-vinylpyrolidone (NVP). A preferred mixture of two monomers (B) is DMAand EOEMA.

The polymerization reaction for the mixture of compounds (A) and (B) toprepare the pigment binder is carried out in an organic solvent mediumutilizing conventional solution polymerization procedures that are wellknown in the art. While it is preferable to polymerize (A) and (B) priorto placement upon the lens or mold, one of skill in the art willrecognize that such polymerization can occur after placement of theconstituents on the mold, for example. Preferably the polymerization iscarried out in the presence of a polymerization initiator.

Suitable polymerization initiators include radical polymerizationinitiators and photo polymerization initiators. Of course, the initiatorchosen will depend upon the type of polymerization carried out. Typicalexamples of radical polymerization initiators includeazobisisobutyronitrile (AIBN), azobisdimethylvaleronitrile, benzoylperoxide, t-butyl hydroperoxide, and cumene peroxide. Such curingcompositions include those available commercially from CIBA SpecialtyChemicals under the “IRGACURE” trade name and from DuPont under the“VAZO” tradename, such as VAZO 64 (AIBN), VAZO 67 (butane nitrile,2-methyl, 2,2′-azobis) and VAZO 88 (cyclohexane carbonitrile,1,1′-azobis).

Typical examples photo polymerization initiators include, a benzoinphoto polymerization initiator such as methyl orthobenzoylbenzoate,methyl benzoylformate, benzoin methyl ether, benzoin ethyl ether,benzoin isopropyl ether, benzoin isobutyl ether or benzoin n-butylether; a phenone photo polymerization initiator such as2-hydroxy-2-methyl-1-phenylpropane-1-one,p-isopropyl-α-hydroxyisobutylphenone, p-t-butyltrichloroacetophenone,2,2-dimethoxy-2-phenylacetophenone, α,α-dichloro-4-phenoxyaceto-phenoneor N, N-tetraethyl-4,4-diaminobenzophenone; 1-hydroxycyclohexyl phenylketone; 1-phenyl-1,2-propanedione-2-(o-ethoxycarbonyl)oxime; athioxanthone photo polymerization initiator such as 2-chlorothioxanthoneor 2-methylthioxanthone; dibenzosvarron; 2-ethylanthraquinone;benzophenone acrylate; benzophenone; and benzil.

The identity of the polymerization initiator is not critical and is notpart of the present invention. One of ordinary skill in the art willreadily recognize the kind and amount of photoinitiator that will yieldgood results in the present invention. The initiator presently preferredby the inventors is VAZO 52, a thermal initiator similar to VAZO 64.

Organic solvents which may be used in the polymerization of thecompounds (A) and (B) include virtually any of the organic solventsknown to be employed in preparing conventional acrylic or vinylpolymers, such as, for example, alcohols, ketones, aromatichydrocarbons, or mixtures thereof. The solvent or solvents employed isor are generally selected based on compatibility with the othercomponents of the binder and like considerations. Illustrative ofsolvents employed alone or admixture in the compositions of theinvention are ketones such as methylethylketone, methylisopropylketone,diethylketone, cyclopenta-none, cyclohexanone and the like; chlorinatedhydrocarbons such as trichloroethylene, 1,1,1-trichloroethane and thelike; aliphatic alcohols such as ethanol, n-propyl alcohol, n-butylalcohol, n-hexyl alcohol and the like; aliphatic esters such as n-butylacetate, n-hexyl acetate, cellosolve acetate, ethyl lactate and thelike; glycol ethers such as ethylene glycol monomethyl ether, propyleneglycol monomethyl ether and esters thereof such as the acetates,propionates and the like; and aromatic hydrocarbons such as toluene,xylene and the like; and aromatic ethers such as anisole.

However, some of the disadvantages mentioned above concerning diluentsin contact lens monomer mixtures may also apply to the solvent systemchosen. Therefore, it may be important to choose a solvent that does notreact with (or reacts very slowly) with the pigment binder. Anynon-nucleophilic organic solvent in which the reactants are soluble andhaving a boiling point at or above the desired reaction temperature maybe used. An inert solvent is one that does not react with either of thestarting materials under the reaction conditions employed. Among theinert solvents that are suitable are liquid halogenated lower alkanes(e.g., methylene chloride, chloroform, 1,2-dichloroethane,1,2-dibromoethane, 1,1,1-trichloroethane and 1-bromo-2-chloroethane) andketones. In this respect, the most preferred solvent is cyclohexanone.The solvent employed should also be compatible with the colorants andnon-destructive toward contact lens materials.

In the preferred embodiment of the present invention, the color coat (orink as it can be referred to prior to application) is stable for atleast four hours. More preferably, the ink is stable for at least eighthours. Even more preferably, the ink is stable for at least two days.Most preferably, the ink is stable for at least one week, or for atleast three weeks. By “stable” with reference to ink, it is meant thatno significant increase in viscosity occurs over a specific time period.A stable ink provides more flexibility in the mass production of coloredophthalmic lenses. The increase in viscosity (also referred to asgelling) is typically caused by crosslinking reactions between thecomponents of the color coat. Accordingly, the color coat is preferablysubstantially free of compounds that crosslink with the binder polymer.

Lenses colored by this invention can be formed from any knownpolymerizable hydrophilic or hydrophobic material suitable forophthalmic uses. Lens forming materials that are suitable in thefabrication of contact lenses are illustrated by numerous issued USpatents and familiar to those skilled in the art.

Preferred polymers for making the lens include those having thefunctional groups —COOH, —OH, and/or —NH—R, where R is hydrogen oralkyl. Polymers having amine functional groups would be more reactive,and thus, would result in a faster curing color coating once it isapplied to the lens. Preferred materials are hydrophilic and absorbsubstantial amounts of water to form hydrogels. Preferred hydrophilicpolymers containing functional groups are formed from e.g., acrylicacid, methacrylic acid, hydroxy C₁ to C₆ alkyl esters of acrylic andmethacrylic acid (e.g., hydroxyethyl methacrylate and hydroxybutylacrylate), amino C₁ to C₈ alkyl esters of acrylic and methacrylic acid(e.g., amino ethyl acrylate or N-ethyl amino methyl methacrylate),glycerol esters of acrylic and methacrylic acid, and mixtures thereof.Exemplary hydrophilic lenses having the functional groups are disclosedin U.S. Pat. No. 4,405,773, (Loshaek) and are formed from a mixture ofhydroxyethyl methacrylate, ethoxyethyl methacrylate, and methacrylicacid.

Producing the lens by polymerization, crosslinking, and/or shaping iswell known in the art and is not presently considered a critical part ofthis invention. Any of the well-known techniques of cast molding andspin casting may be employed.

When compounds (A) and (B) are incorporated into a binder polymer, theywill enable the binder polymer to crosslink in the presence of a reagentsuch as water. They are also reactive with other materials such thosecontaining the functional groups —OH, —NH₂, and NHR, where R is alkyl.The crosslinking could be done during the lens hydration and/orsterilization step. This aspect has the advantage that a separateadhesion promoter species is not needed and crosslinking could beaccomplished in the lens sterilization step, the lens hydration step, orduring a separate cure step. Monomers and an initiator may be, but donot need to be (and are preferably not), added to the ink.

The viscosity of the binder polymer as it applied to the lens materialis important for maintaining print quality. The viscosity of an inksolution can be as high as about 5,000 centipoise, but is preferablybetween about 1 to about 1000 centipoise. The optimal viscosity of thecolor coat is determined largely by the method by which the coat isapplied to the lens. For example, if the color coat is to be applied byink jet printing, the viscosity of the ink should be less than 50centipoise, preferably less than 30 centipoise, and most preferablyequal to or less than 15 centipoise. On the other hand, if the ink is tobe applied by pad printing, the viscosity is preferably above 100centipoise; more preferably above 200 centipoise.

Solutions having low viscosity tend to be “runny” when dispensed, andcan allow different colors to merge and blend, resulting in an imagewith a more natural appearance. Such blending can be enhanced using avariety of methods, including sonication or vibration at appropriateduration and frequency to promote appropriate blending. Solutions havingtoo low a viscosity can result in images that are too “runny” and thushave potentially, undesirable characteristics, such as pooling of ink ina pattern or spreading of ink to an unintended location. The skilledartisan will recognize that the size of the ink droplet as applied tothe lens and the surface tension thereof will also influence thebehavior of the ink when printed on a lens or a mold. Thus, depending onthese factors, the viscosity of the ink may vary from the numbers givenabove and still function within the scope of this invention.

Solutions having too high a viscosity may not be easily dispensed usinga variety of printing structures, such as inkjets and thus may not beappropriate for the present invention. Furthermore, solutions havinghigh viscosity can tend to “bead” on a surface and not blend with thesurrounding environment, including surrounding droplets or beads of ink.Under these circumstances, the ink may form unnatural appearing images.

Agents such as thickeners or appropriate solvents can be used to adjustthe viscosity of the color coating composition. Such agents arepreferably non-nucleophilic in nature.

The lenses may be prepared with or without an optical prescription forcorrecting visual defects. The lenses may contain an opaque color coatwhich can bring about a fundamental color change in the apparent colorof the wearer's iris, for example from dark brown to light blue.Alternatively, the color coat may be transparent, in which case theapparent eye tint may be enhanced, or the apparent color oflight-colored eyes may be changed. “Enhancing lenses,” allow the naturaliris to show through but combine with that natural color to produce anew appearance. Such enhancing lenses might typically be used to turn ahazel eye to an aqua colored eye. However, this class of colored lensesmay not be able to change an underlying dark colored, brown iris toblue.

Not only is it possible to choose from entirely opaque or entirelytransparent color coats, but also it is preferable to color selectedportions of the lens. Specifically, it is preferable to color the lensin a pattern that simulates the fine structure of the iris, preferablyusing more than one color. Alternatively, it is possible to deposit anopaque or semi-opaque pattern over the iris portion of the lens in amanner that can change the apparent color of the iris, as described inU.S. Pat. No. 5,414,477 to Jahnke. It is well recognized that thepattern of the color coat on or in the lens is a significant factor inthe apparent cosmetic quality of the lens. The lenses are quite durableand retain their color upon prolonged use, even though subjected to theusual disinfecting and cleaning procedures. The colorant used in thecolor coat need not be reactive.

The color coat can be placed on lens in the dry state, a lens in a wetstate, or on the mold by a variety of printing procedures. In fact, thecolor coat could be painted on the lens or mold with a brush. Obviously,in the commercial manufacture of the lens, it is more desirable to printthe pattern onto the lens surface or the mold surface using well knownand understood automated techniques, such as by pad-transfer printingfrom an etched plate of the pattern using a soft rubber pad, such as onemade of polydimethylsiloxane rubber, and equivalent materials. Thepattern may be created on the lens or on the mold with an airbrush, orby ink jetting, and the like methods of coating the colored film ontothe mold. Alternatively, the color coat may be injected from a diehaving a face that conforms to the shape of the lens or mold surface andpossessing holes in the face configuring to the iris section on themold's surface. The holes replicate the pattern to be coated on the lensor mold. The die can be dropped to the surface of the lens or mold likea date stamper, and the pressure on the die face can be used to forcethe colored material out of the die onto the lens or mold.

In pad-transfer printing, an image is placed or printed on a padtransfer device and the image on tile pad transfer device is transferredto another surface, such as a polymer or lens (U.S. Pat. Nos. 3,536,386to Spivack; 4,582,402 and 4,704,017 to Knapp; 5,034,166 to Rawlings etal.). For example, appropriate pad-transfer printing structures include,but are not limited to Tampo-type printing structures (Tampo vario90/130), rubber stamps, thimbles, doctor's blade, direct printing, ortransfer printing as they are known in the art.

When the color coat is applied to the lens mold, rather than to the lensitself, the color coat is applied to a surface of the mold and the moldis then charged with the lens forming monomer while maintaining thecolor coat in the iris portion and configuring the resin about the colorcoat. The lens monomer is then polymerized using any of the well-knownpolymerization techniques. Alternatively, if the lens formingcomposition is a polymer (such as poly(vinyl) alcohol) the compositionis then cross-linked according to well-known techniques. In this mannerthe color coat becomes integral with the body of the lens when themolded lens is removed from the mold. The resulting lens is essentiallysmooth and continuous on the surface containing the color coat.

In the preferred embodiment, the color coating of the present inventionhas good transferability to a medical device. “Good transferability” inreference to a color coat means that a color image printed on a moldwith the color coat will be transferred completely onto the medicaldevice cured in that mold.

More than one printing structure or more than one printing method can beused to make an image with the method of the present invention. Forexample, ink-jet printing and pad transfer printing can be used incombination.

If the lens is intended to be natural in appearance, the color coatpreferably contains voids. Typically the voids comprise about 5 to about80% of the color coat's area. On the other hand, it is preferred thatthe color coat occupy from 50% to all of the area of the lens in theiris region thereof (or that portion of the mold corresponding to theiris region of the lens).

While, either the front or rear surface or both may be coated, it ispreferable to apply the color coat to the front surface of the lens.However, there are special cosmetic effects achievable by providing apattern on both the anterior and posterior surfaces. For instance, acolored pattern of one color can be applied to the back surface of thelens or the corresponding mold-half (for instance, white) and the sameor different colored pattern can be applied to the front surface of thelens or the corresponding mold-half (for instance, dark blue). This thenwould result in a lens that could have either a multi-color texturedappearance for extremely lifelike appearance, or a brighter tint using awhite background to reflect back out at the observer.

If the color coat is applied to both sides of a lens by printing up bothsides of the mold, a pattern is affixed to both the back surface and thefront surface molds as aforedescribed. Part of the lens-forming monomermixture is supplied to each of the mold halves and each is partiallypolymerized thus fixing the patterns to the front and back surfaces ofthe lens. The two mold halves are combined, and the combination isinterpolymerized to complete the cure and the formation of the lens withthe patterns on both surfaces

The coated lens is then subjected to conditions that cure the colorcoat. If the colorant is opaque, then only the portion of the lenscorresponding to the iris is usually coated, leaving the pupil sectionclear. For lenses that are larger in diameter than the iris, the portionof the lens extending beyond the iris may be left uncoated.

In any event, it is important that the resulting lens be ophthalmicallycompatible. Accordingly, while any suitable colorant may be employed, itis presently preferred that the colorant be a pigment that is heatresistant, non-toxic and insoluble in aqueous solutions. While notcritical to the invention, the particle size of the pigments used in thepresent invention generally varies from about 0.02 microns to about 5microns, with the preferred size of particle depending on the method ofprinting.

The choice of pigments is quite flexible, since they need notnecessarily contain functional groups. The pigments may be any coloringsubstance or combination thereof that provides a desired color.Preferred pigments include (C.I. is the color index no.) for a bluecolor, phthalocyanine blue (pigment blue 15, C.I. 74160), cobalt blue(pigment blue 36, C.I. 77343); for a green color, phthalocyanine green(Pigment green 7, C.I. 74260) and chromium sesquioxide; for yellow, red,brown and black colors, various iron oxides; for violet, carbazoleviolet. Of course, since any color can be obtained by merely mixing twoor more primary colors together, blends of such primary colors are usedto achieve the desired shade. As defined herein, “primary colors” meancyan, magenta, and yellow. Titanium dioxide can be added to the colorcoat to increase the opacity of the color coat.

In general, the amount of colorant added to the organic binder is offrom about 10 to about 80% preferably from about 20% to about 50% byweight of the total pigment-binder composition. A white pigment-bindercomposition may contain of from about 40 to about 60% by weight ofpigment based on the weight of the pigment-binder composition, while ablack pigment-binder composition may contain of from about 30 to about60% by weight of the pigment-binder composition. A red pigment-bindercomposition may contain of from about 33 to about 50% by weight of thepigment-binder composition. A blue pigment-binder composition maycontain of from about 32 to about 50% by weight of the pigment-bindercomposition, while a yellow pigment-binder composition may contain offrom about 33 to about 50% by weight of the pigment-binder composition.

The inks disclosed herein may contain dispersants. Dispersants aresurface active agents added to promote the distribution and separationof fine particles, such as, for example, the Tergitol series from UnionCarbide, polyoxylated alkyl ethers, alkyl diamino quarternary salts,surfynol, Pluronic, Pluronic R, or PECEGAL “0” from GAF (U.S. Pat. No.5,560,766).

Dispersants are preferably not used if the method of printing is padprinting. However, when the method of printing is ink jet printing, adispersant or other surfactant is preferably employed. If present, arepreferably used at between about 0.1% and about 10%, more preferablybetween about 0.5% and about 5%. However, because of the presence ofactive hydrogens in various surfactants, the surfactant may causepremature gelling. Thus, it is preferable to use surfactants in whichthe hydroxyl groups are either masked or protected. For example, it maybe preferable to use polyethylene glycol surfactants in ether-terminatedform. Furthermore, surfactants terminated in secondary hydroxyl groups(such as the PLURONIC R series) are preferable over those terminated inprimary hydroxyl groups (such as the PLURONIC series).

Opaque coloring agents can be applied to a surface more than once toobtain the desired intensity, hue, or other color characteristic. Eachapplication of the color coat can be printed in the same or differentpattern, and can be printed in the same or different manner.

After coating, the lens is subjected to conditions that cause the colorcoat to adhere to the lens, thereby entrapping the colorant within thebinding polymer in a manner that forms a colored contact lens. Thecoated lens, for example, may be subjected to UV radiation, heat, ormoisture. The moisture can either be in the form of water vapor orliquid water. Of course, any conditions that crosslink the binderpolymer and thus, bring about adhesion of the color coat, may be used.

The step of subjecting the lens to conditions that cure the binder maybe combined with other steps in the lens manufacturing process. Forexample, if it is desired to cure the binder With heat, this could bedone during the lens sterilization process when the lens is subjected tohigh temperatures. Alternatively, the binder can be water cured duringthe lens hydration step in which the lens is exposed to water for anextended amount of time. Thus, it is not necessary to have a separatestep of curing the binder, thus simplifying the manufacturing processand reducing costs. However, when curing the color coat in a hydrationstep it is necessary to ensure that the color coat does not delaminatefrom the lens upon being placed into the water.

In some embodiments of the present invention, it may not even benecessary to expose the lens to such conditions, as the lens itselfprovides the necessary impetus for the binder to cure. For example, inthe case of a water-curable binder, the very act of applying the colorcoat to a hydrated lens will begin the curing process. This isespecially appropriate in the case of crosslinked polyvinyl alcohollenses, which are formed in a hydrated state. (See, for example, U.S.Pat. No. 5,508,317). Likewise, if the color coat is applied to a lenscomprising a polymer having functional groups as disclosed above, thebinder will adhere to the lens without a distinct step of exposing thelens to moisture or heat. However, due to the rapid automated processtypically used in present lens manufacturing processes, it may bedesirable to speed the curing process, rather than wait the necessarytime for un-aided curing.

The previous disclosure will enable one having ordinary skill in the artto practice the invention. In order to better enable the reader tounderstand specific embodiments and the advantages thereof, reference tothe following non-limiting examples is suggested. However, the followingexamples should not be read to limit the scope of the invention.

EXAMPLE 1

A binder polymer was synthesized at 40° C. under nitrogen for 25 hourswith the following formulation

Component Wt % DMA 57 EOEMA 37 methacryloxypropyltrimethoxysilane 5Vazo-52 0.54 Toluene 250 ml

The viscosity of the resulting binder was 75 cps at 22° C.

EXAMPLE 2

An ink preparation was prepared by combining 10 g of the toluene polymersolution of Example 1 with 0.250 g of Permetjet Blue and stirred for 30minutes. The viscous solution was filtered (2.7 micron filter) to removeunsolubilzed colorant.

EXAMPLE 3

Six Freshlook® lenses (phemfilcon) were tested for print adhesion undera variety of conditions. Excess water was removed from the lenses and aquantity of the ink formulation of Example 2 was placed on each lenswith a syringe. As put forth in Table 1, the lenses were put through acombination of steps including a print cure step; an autoclave step; anda hydration step. The print cure step comprises subjecting the lens to atemperature of 85° C. for 45 minutes. The autoclave step comprisessubjecting the lens to a temperature of 120° C. for 40 minutes. Thelenses were hydrated for 45 minutes and put into packaging solutionbefore being autoclaved.

The Print Adhesion test was performed by sonicating the lenses inmethanol for 30 seconds, equilibrating for five minutes in saline buffersolution, and then rubbing the surface with a finger or a swab forapproximately 10 seconds.

TABLE 1 Lens Hydrated Print Cured Autoclaved Print Adhesion A N Y Y F BN Y N F C Y N N F D Y Y N P E Y N Y P F Y Y Y P

EXAMPLE 4

A variety of inks were prepared by combing the binder of Example 1 withvarious pigments: Permajet Blue (1%); Iron Oxide Black (10%); andPhthalocyanine Blue (1%).

EXAMPLE 5

Nine hydrated Freshlook® lenses (phemfilcon) were tested for printadhesion under a variety of conditions. Excess water was removed fromthe lenses and a quantity of each ink formulation of Example 4 wasplaced on each lens with a syringe. As put forth in Table 2, the lenseswere put through a combination of steps including a print cure step; anautoclave step; and a hydration step. The print cure step comprisessubjecting the lens to a temperature of 85° C. for 45 minutes. Theautoclave step comprises subjecting the lens to a temperature of 120° C.for 40 minutes. The lenses were hydrated for 45 minutes and put intopackaging solution before being autoclaved.

TABLE 2 Pigment Print Cured Autoclaved Print Adhesion Permajet Blue Y NP Permajet Blue Y Y P Permajet Blue N Y P Iron Oxide Y N P Iron Oxide YY P Iron Oxide N Y F Phthalocyanine Blue Y N P Phthalocyanine Blue Y Y PPhthalocyanine Blue N Y F

The non-print cured iron oxide and phthalocyanine lenses are indicatedas a “fail” because the ink delaminated when the lenses were placed inthe hydration solution prior to autoclaving.

EXAMPLE 6

The binder of Example 1 was precipitated with hexane and dried overnightin a vacuum at 40° C. To prepare inks with various solvents, 1 g ofbinder was dissolved in 10 ml solvent and 1% (by weight) of PermajetBlue was then added. Inks were prepared with toluene, cyclohexanone,cyclohexanone:methylethylketone (1:1); cyclohexanone:ethyl lactate(56:44); and cyclopentanone:ethyl lactate:HEMA (42.1:33.2:24.7). Theformulation containing cyclohexanone:ethyl lactate gelled after onehour; the formulation containing cyclopentanone:ethyl lactate:HEMAgelled after three hours; and the formulation containing toluene gelledin 3 days. The siloxane groups on the binder polymer react withnucleophiles like hydroxyl groups. The gelling observed in the tolueneformulation has been postulated to be an interaction with the permajet'sphthalocyanine surface modification. The inks containing cyclohexanonedid not gel, even after three weeks.

EXAMPLE 7

Nine hydrated Freshlook® lenses (phemfilcon) were tested for printadhesion under a variety of conditions. Excess water was removed fromthe lenses and a quantity of each ink formulation of Example 6 wasplaced on each lens with a syringe. As put forth in Table 3, the lenseswere put through a combination of steps including a print cure step; anautoclave step; and a hydration step. The print cure step comprisessubjecting the lens to a temperature of 85° C. for 45 minutes. Theautoclave step comprises subjecting the lens to a temperature of 120° C.for 40 minutes. The lenses were hydrated for 45 minutes and put intopackaging solution before being autoclaved.

TABLE 3 Solvent Print Cured Autoclaved Print Adhesion Toluene Y N PToluene Y Y P Toluene N Y F Cyclohexanone Y N P Cyclohexanone Y Y PCyclohexanone N Y F CH:MEK (1:1) Y N P CH:MEK (1:1) Y Y P CH:MEK (1:1) NY F

The non-print cured lenses are indicated as a “fail” because the inkdelaminated when the lenses were placed in the hydration solution priorto autoclaving. A more rapid cross-linking reaction upon exposure tomoisture would most likely prevent the delamination.

It is to be understood that the foregoing description and specificembodiments are merely illustrative of the best mode of the inventionand the principles thereof, and that various modifications and additionsmay be made to the apparatus by those skilled in the art, withoutdeparting from the spirit and scope of this invention, which istherefore understood to be limited only by the scope of the appendedclaims.

1. A method for making a colored contact lens comprising the steps of:(a) coating at least a portion of at least one lens-forming surface of alens mold with a color coat comprising at least one colorant, and abinder polymer obtained by copolymerizing polymerizable componentscomprising a. a first monomer being ethylenically unsaturated and havinga latent crosslinkable pendent group selected from the group consistingof alkoxysilane, silanol, acetoxysilane, silanes, halosilane, andcombinations thereof; and b. a second monomer having an ethylenicallyunsaturated double bond copolymerizable with the first monomer; whereinthe second monomer is substantially non-reactive with the latentcrosslinkable group of the first monomer; and (b) adding a lens formingcomposition to the lens mold while maintaining the color coat inposition; (c) curing the lens-forming composition to form a contact lenswith the color coat thereon; (d) activating hydrolytic or non-hydrolyticcrosslinking reactions for crosslinking the latent crosslinkable groupsin the color coat on the contact lens, thereby causing the color coat toadhere to the lens, wherein the step of activating hydrolytic ornon-hydrolytic reactions is carried out by subjecting the contact lenswith color coat thereon to at least one condition selected from thegroup consisting of exposure to moisture, exposure to nucleophiliccatalysis, exposure to alkoxy silane, exposure to metal oxides, exposureto a mixture of alcohol and carboxylic acid, exposure to silanols,exposure to acetoxysilanes, exposure to carboxylic acids, and exposureto acids, heat, or combinations thereof.
 2. A method as claimed in claim1, wherein said hydrolytic or non-hydrolytic crosslinking reactions forcrosslinking the latent crosslinkable pendent groups in the color coaton the contact lens are activated by exposing the lens to moisture,heat, nucleophilic catalysis, or combinations thereof.
 3. A method asclaimed in claim 1, wherein said latent crosslinkable pendent group isselected from the group consisting of silanol, acetoxysilane, silanes,and combinations thereof.
 4. A method as claimed in claim 1, whereinsaid latent crosslinkable pendent group is selected from the groupconsisting of alkoxysilane and halosilane.
 5. A method as claimed inclaim 4, wherein said first monomer is a polymerizable halosilane oralkoxysilane compound of the formula (I):

wherein X is a polymerizable group containing an unsaturated doublebond; n is an integer from 0 to 12; Z is either a halide or —OR₂; eachR₁ is, independently of any other, a halide, or a substituted orunsubstituted C₁₋₆ alkyl group; R₂ is, independently of any other, asubstituted or unsubstituted C₁₋₆ alkyl group and q is an integer from 1to
 3. 6. A method as claimed in claim 5, wherein X is a (meth)acryloxygroup, vinyl group, an allyl group, or a group of the formula


7. A method as claimed in claim 6, wherein X is a (meth)acryloxy groupor a vinyl group.
 8. A method as claimed in claim 5, wherein n is from 2to 3, and X is a methacryloxy group.
 9. A method as claimed in claim 5,wherein Z is —OR₂ and q is
 3. 10. A method as claimed in claim 5,wherein said first monomer is selected from the group consisting ofmethacryloxyethyltrimethoxysilane,methacryloxyethylmethyldimethoxysilane,methacryloxyethyldimethylmethoxy-silane,methacryloxyethyltriethoxysilane, methacryloxyethylmethyldiethoxysilane,methacryloxyethyldimethylethoxysilane, methacryloxyethyltrichlorosilane,meth-acryloxypropyltrimethoxysilane,methacryloxypropylmethyldimethoxysilane,methacryloxypropyldimethylmethoxysilane,methacryloxypropyltriethoxysilane,methacryloxypropymethyldiethoxysilane,methacryloxypropyldimethylethoxy-silane, styrylethyltrimethoxysilane,and 3-(N-styrlmethyl-2-aminoethylamino) propyltrimethoxysilanehydrochloride.
 11. A method as claimed in claim 5, wherein at least oneR₂ is a methyl group.
 12. A method as claimed in claim 9, wherein atleast one R₂ is a methyl group.
 13. A method as claimed in claim 5,wherein said first monomer is selected from the group consisting ofmethacryloxyethyltrimethoxysilane,methacryloxyethylmethyldimethoxysilane, andmethacryloxyethyldimethylethoxy-silane.
 14. A method as claimed in claim9, wherein Z is a halide.
 15. A method as claimed in claim 5, whereinsaid first monomer is selected from the group consisting ofmethacryloxypropylmethyldichlorosilane,methacryloxypropyltrichiorosilane,3-methacryloxypropyldimethylchlorosilane, andmethacryloxyethyltrichlorosilane.
 16. A method as claimed in claim 3,wherein said second monomer is silicon-free.
 17. A method as claimed inclaim 1, wherein the second monomer does not contain hydroxy functionalgroups, primary and secondary amine functional groups, or acidfunctional groups.
 18. A method as claimed in claim 1, wherein thesecond monomer is selected from the group consisting of N-vinylheterocyclic monomers, C₁ to C₆ alkyl vinyl ethers, C₁ to C₆ alkylesters of acrylic or methacrylic acid, C₁ to C₆ alkyl styrenes, vinylmonomers, diene monomers, and C₁ to C₆ alkoxy C₁ to C₆ alkyl esters ofacrylic or methacrylic acid.
 19. A method as claimed in claim 18,wherein the second monomer is selected from the group consisting ofN-vinyl heterocyclic monomers and alkyl (meth)acrylamides.
 20. A methodas claimed in claim 19, wherein the second monomer is selected from thegroup consisting of N,N-dimethyl acrylamide and N-vinylpyrolidone.
 21. Amethod as claimed in claim 1, wherein said step of activating hydrolyticor non-hydrolytic crosslinking reactions for crosslinking the latentcrosslinkable groups in the color coat on the contact lens is carriedout during a hydration step of the lens.
 22. A method as claimed inclaim 1, wherein said step of activating hydrolytic or non-hydrolyticcrosslinking reactions for crosslinking the latent crosslinkable groupsin the color coat on the contact lens is carried out during hydrationand sterilization steps of the lens.